arrays/numbers/strings

javascript/array.test.js

@@ -0,0 +1,11 @@
+const array = require('./array')
+
+test('sum array values', () => {
+  expect(array.sum([1,2,3])).toBe(6)
+  expect(array.sum([])).toBe(0)
+})
+
+test('sum object array', () => {
+  expect(array.sumObj([{x:1}, {y:2}, {z:3}])).toBe(6)
+  expect(array.sumObj([])).toBe(0)
+})

javascript/number.js

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+module.exports.base7 = num => {
+	result = ''
+	while (num > 0) {
+		result = `${num % 7}${result}`
+		num = Math.floor(num / 7)
+	}
+
+	return parseInt(result)
+}

javascript/number.test.js

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+const number = require('./number')
+
+test('convert number to base7', () => {
+	expect(number.base7(384605)).toBe(3161204)
+	expect(number.base7(7)).toBe(10)
+	expect(number.base7(6)).toBe(6)
+})

javascript/string.js

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+module.exports.indexOf = (str, word) => {
+	for (let i = 0; i < str.length; i++) {
+		for (let k = 0; k < word.length; k ++) {
+			if (str[i + k] !== word[k]) {
+				break
+			}
+
+			if (k === word.length - 1) {
+				return i
+			}
+		}
+	}
+	return -1
+}

javascript/string.test.js

@@ -0,0 +1,8 @@
+const string = require('./string')
+
+test('indexOf', () => {
+	expect(string.indexOf('abcdef', 'cde')).toBe(2)
+	expect(string.indexOf('abcdef', 'zzz')).toBe(-1)
+	expect(string.indexOf('abcdef', 'f')).toBe(5)
+	expect(string.indexOf('aaaaa', 'a')).toBe(0)
+})